The invention is generally related to structural concrete forms, and more particularly to a form and to a method of using the form for producing concrete structures wherein the form has an openable top beam.
Concrete forms for fabricating structural concrete beams such as stadium raker beams, bridge bents or beams, and the like are well known. The self-spanning method or technique is often utilized to form such structures and is also well known. This type of form typically has opposed, spaced apart side panels, a hinged bottom soffit panel and a top opening extending along a longitudinal axis of the form. These forms also typically have a plurality of top beams arranged transverse to the longitudinal axis of the form and spanning the top opening. The top beams are fixed to the top edges of the side panels to add adding structural rigidity and to square up the form. The hinged soffit panel is openable so that the form can be removed or lifted in one piece from a cured, formed concrete section such as a stadium raker or bridge bent.
This type of concrete form requires at least partial dismantling and reassembly to a degree necessary for installation or setting of reinforcement steel within the form. The reinforcement steel can include a plurality of elongate steel rebar rods, a preformed rebar cage, or any other suitable reinforcement. The steel is set in the form through the top opening. Therefore, the top beams must be removed in order to place the steel.
The conventional manner of using this type of hinged bottom soffit panel form includes first fully assembling the form and then placing the form with a crane or other lifting device in the installation position where the raker, bent, or other concrete structure will be used. The top pieces including the top plurality of top beams must each then be removed to provide access to the top opening. The steel is set in place through the open top of the form. The top pieces are then reinstalled and secured over the top opening.
After the steel reinforcement is set in the form, the concrete is then poured or otherwise added to the form. After the concrete is sufficiently cured, the soffit panel is opened or dropped and the form is lifted in one piece from the cured concrete structure and either placed on the ground or at a new installation position. To subsequently use the form at a different installation position, it must again be partly dismantled to the degree necessary to set new steel reinforcement elements therein and then be reassembled again. This process is time consuming and can therefore add significantly to both labor cost and construction time.
It is also possible, as an alternative, to set the steel in the form for each use while the form is on the ground. The fully assembled form and installed steel reinforcement can be lifted together to the installation position. However, each subsequent use of the form still requires the time consuming process of dismantling all top pieces in order to set new steel in the form. Further, the steel reinforcement adds significant weight to the form. Lifting the form and steel together will likely increase the required size and load capability of the crane. This can add significant cost to a particular job.